Terrain parks are like opinions - just about everybody's got one. According to statistics compiled by National Ski Areas Association, almost 90 percent of all winter mountain resorts in the United States have some sort of terrain park.

The Pacific Northwest is case in point. The majority of the two dozen resorts in Oregon and Washington have some sort of terrain park.

"Resorts have come to the conclusion that terrain parks are on the list of to-do options," says Mike Bettera, senior projects manager of Snow Park Technologies, whose clients include the Winter X Games in Aspen. "Terrain parks are something you must have."

Loosely defined, a terrain park is a special, set-aside area of a resort that allows skiers and snowboarders to play on in-snow features such as rails, boxes, stairs, and other similar (generally metallic) protuberances.

Park rats, as the generally youthful TP denizens are called, then slide across, bounce off, or jump over these features with varying degrees of skill and a great amount of enthusiasm.

"It's totally a social thing," says Bettera. "It comes from urban skateboarding where kids like to simply hang out. It's truly different from the back-country (skiing and snowboarding) experience."

Terrain parks vary greatly. "A good park is one that has multiple levels of progress," says Bettera. "You have small, non-intimidating features for (neophytes) getting the feel of going over them. Then you have medium-size features that create a good line with multiple hits that are fun for people no matter how well they ride. Then you have large features for the showboats to dial in big tricks.

"You can tell the better parks by the amount of commercial branding they use. Also by the way they look and are presented through the use of flags, fencing, music, animation, and other fun stuff - the things that bring liveliness and life to the park."

On the other hand, Bettera says, you can tell when a resort just doesn't care about park rats.

"There's not a lot of allocation of resources," he says. "They don't maintain the park on a daily basis ,or the trail is hidden or is not pushed or marketed by the resort or it's not branded."

Here is a look at what Oregon and Washington have to offer in the way of terrain parks:

Paradise Parks at Mt Hood Meadows is a freestyle terrain experience featuring six different parks, each themed to reflect the Portland lifestyle. There's Park Place, the resort's original park, which is set up for advanced riders; Rose City Park, which has rails, jibs, and jumps suitable for intermediate to advanced riders; The Zoo, whose small rollers and jumps are geared for newbies; Shipyard, which is the resort's early-season park, and the Superpipe, a 500-foot-long, 18-foot high in-ground playground.

Mt Bachelor has four parks running the gamut from easy to radical. Sunshine Park has small features suitable for those just getting comfortable with park life; iPark has medium-sized features for intermediates looking to improve their skills; Slopestyle has large features, and 1-5 is a mile-long playground with 1,200 vertical feet of medium to large features.

The Summit at Snoqualmie has three parks, two of which are lit up for night riding six days a week. Greenhorn Acres is a progression park to help beginners start their terrain park experience; Central Park, which requires a resort-issued park pass, is the place for better riders, and West 52nd is suitable for beginner to intermediate riders and is open only on weekends.

Timberline Lodge has situated its terrain park off the Stormin' Norman express quad, with large features on the Spray Paint and Paint Brush runs, medium features on the Conway's and Bonezone runs, and small features on the Glade and Blossom runs.

In order to access Mission Ridge's B24 terrain park, you must go through a user awareness and safety program and then purchase a park pass, which is good for the entire season.

Mt Spokane has a progression park featuring hits for everyone on the Half Hitch and Lamonga Pass runs.